SOLUTION: class 4 instead of class 10!
https://code.google.com/p/android/issues/detail?id=2500#c293
http://forums.androidcentral.com/verizon-droid-charge/213468-droid-charge-damaged-sd-card-error-won-t-mount-fix-8.html#post5126775

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SYNC!!!
https://code.google.com/p/android/issues/detail?id=2500#c290
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https://code.google.com/p/android/issues/detail?id=2500
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well.... fml
but see tweet chain from here:
https://twitter.com/respeccing/status/718804856463572992

looks like it corrupts the sdcard, maybe becuase it lacks a sync!!! even tho
it does execute umount!
OR the sdcard internally postpones the sync, but android cuts power too
soon!(esp. during reboot! and when switching between 'USB Storage' and 'Media...
(MTP)')

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can only fix it by mounting it on the computer as RW, deleting something like
LOST.DIR(even tho it was empty) and then umount, eject; put in phone works!
//well looks like that only works sometimes!!!!!!!!
* reboot phone and it's back to fucked again!
  * test: if unmount first works! (tested it once but didn't work, but maybe
    mount does some damage anyway! didn't test if remount works, without first
    rebooting!)
* test: don't reboot phone, unmount, replug, works; or unmount, unplug, plug, works!
* running fsck.vfat -v -f -V /dev/sdd1  without mounting it as rw(or ro) still
  yields damaged SD card when put in phone!
* just mounting it as rw(on linux), then umount, then eject - still damaged!
* fix: must mount and write something(ie. delete LOST.DIR which fsck created!)
  on it before umount! - nope, that didn't do it this time! still damaged!
  re-plugging in PC, running a fsck(as above), twice!... nope, still damaged
  (tho, there's not LOST.DIR anymore!) - replug, mount rw, delete dir
  '/backup', umount, eject; still damaged; replugged, now fsck! reports an
  error: Reclaimed 4 unused clusters (131072 bytes) in 4 chains.
* still damaged shiet... and yet it works just fine on PC (via card reader..)

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this happened even when Quick Boot is off!!! just a reboot will do!
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doing a lark reboot, while having Fast Boot selected(maybe even if not!) will
not unmount external sdcard safely and thus it's detected as damaged and
unmountable on next boot!

fucking great job Android!!!

Fast Boot is named Quick Boot, is under Accessibility (in Settings)


Looks like plugging the card in the laptop worked fine! no errors! So it
must've been the Quick Boot! it probably works if I plug it back in again now!

